Το κείμενο της παρουσίασης

•The slides in this presentation are made from theWSDL tutorial of W3Schools, available athttp://www.w3schools.com/wsdl/default.asp

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What is Web Service

•Definition: A Web service is a software systemdesigned to support interoperable machine-to-machine interaction over a network.

–It has an interface described in a machine-processableformat (specifically WSDL).

–Other systems interact with the Web service in a mannerprescribed by its description using SOAP messages,typically conveyed using HTTP with an XML serialization inconjunction with other Web-related standards.

From: http://www.w3.org/TR/ws-arch

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The General Process of Engaging a Web Service

From: http://www.w3.org/TR/ws-arch

Introduction to WSDL

WSDL is an XML-based language todefine Web services and how to accessthem.

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What You Should Already Know

•Before you study the WSDL tutorial, youshould have a basic understanding of XMLNamespaces and XML Schema.

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What is WSDL?

•Web Services Description Language

•written in XML

•an XML document

•used to describe Web services

•also used to locate Web services

•not a W3C standard

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WSDL Describes Web Services

•WSDL stands for Web Services DescriptionLanguage.

•WSDL is a document written in XML.

•The document describes a Web service.

•It specifies the location of the service and theoperations (or methods) the service exposes.

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WSDL will Become a W3C Standard

•WSDL is a suggestion by Ariba, IBM and Microsoft fordescribing services for the W3C XML Activity on XMLProtocols.

•A W3C Note is made available by the W3C fordiscussion only. Publication of this Note by W3Cindicates no endorsement by W3C or the W3C Team, orany W3C Members.

•Work in progress at W3C indicates that WSDL mightbecome a W3C Working Draft before the end of 2002,and an official Recommendation before the end of year2003.

•9 July 2002:

W3C has released the first public WorkingDraft of WSDL 1.2!

WSDL Documents

A WSDL document is just a simple XMLdocument. It contains set of definitionsto define a web service

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The WSDL Document Structure

•A WSDL document defines a web service usingthese major elements:

<portType>:The operations performed by the web service

<message>:The messages used by the web service

<types>:The data types used by the web service

<binding>:The communication protocols used by the web service

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<definitions>

<types>

definition of types........

</types>

<message>

definition of a message....

</message>

<portType>

definition of a port.......

</portType>

<binding>

definition of a binding....

</binding>

</definitions>

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WSDL Ports

•The<portType>

element is the most important WSDLelement.

•It defines a web service, the operations that can beperformed, and the messages that are involved.

•The <portType> element can be compared to a functionlibrary (or a module, or a class) in a traditionalprogramming language.

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WSDL Messages

•The<message>

element defines the data elements ofan operation.

•Each messages can consist of one or more parts. Theparts can be compared to the parameters of a functioncall in a traditional programming language.

•Additionally, cross platform programming features areaddressed by adopting SOAP, known as XML Protocolmessaging specifications found at the W3C Web site.

UDDI Benefits

•Any industry or businesses of all sizes can benefit fromUDDI

•Before UDDI, there was no Internet standard forbusinesses to reach their customers and partners withinformation about their products and services. Nor wasthere a method of how to integrate into each other'ssystems and processes.

•Problems the UDDI specification can help to solve:

–Making it possible to discover the right business from themillions currently online

–Defining how to enable commerce once the preferredbusiness is discovered

–Describing services and business processesprogrammatically in a single, open, and secureenvironment

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How can UDDI be Used

•If the industry published an UDDI standard for flightrate checking and reservation, airlines could registertheir services into an UDDI directory.

•Travel agencies could then search the UDDI directory tofind the airline's reservation interface.

•When the interface is found, the travel agency cancommunicate with the service immediately because ituses a well-defined reservation interface.

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Who is Supporting UDDI?

•UDDI is a cross-industry effort driven by all majorplatform and software providers like Dell, Fujitsu, HP,Hitachi, IBM, Intel, Microsoft, Oracle, SAP, and Sun, aswell as a large community of marketplace operators,and e-business leaders.